Tap-changing system and apparatus for transformers



L. H. HILL 1,861,217

TAP CHANGING SYSTEM AND APPARATUS FOR TRANSFORMERS May 31, 1932.

Filed May '7, 1929 3 Sheets-Sheet 1 AAAIA Inventor Leland H. Hill Attorney May 31, 1932; L. H HILL 1,861,217

TAP CHANGING SYSTEM AND APPARATUS FOR TRANSFORMERS Filed May '7, 1929 I5 Sheets-Sheet 2 Fig. 5.

Inventor Leland H. Hill y 1 v \i m v A Home] May 31, 1932.

TAP CHANGING SYSTEM AND APPARATUS FOR TRANSFORMERS H, HILL 1,861,217

Filed May 7, 1929 3 Sheets-Sheet 3 Fig. 14.

Fig. 75

196 H 04 /A97 N0 W m Inventor Leland H. Hi ll WM Q A ttorney after appear. 7

For the purpose of illustrating the inven-' Patented May 31, 1932 v UNITED, STATES PATENT OFFICE LELAND H. HILL, GOLLINGSWOOD, NEW JERSEY, ASSIGNOB, IBY HESNE ASSIGN- MENT S, TO ALLIS-GHALMERS MANUFACTURING COMPANY, OF MILWAUKEE, WIS- CONSIN, A CORPORATION DIE DELAWARE TAP-CHANGING SYSTEM AND-APPARATUS FOR TRANSFORMERS Application filed Kay 7, 1929. Serial no. 361,029.

This invention relates to improvements in tap-changing systems and apparatus for transformers.

One of the objects of the present inven tems and a paratus proposed heretofore.

Other ob ects and advantages will hereintion, several embodiments thereof are shown in the drawings, wherein Figure 1 is a schematic showing of a tapchangin'g'system and apparatus for transformers embodying the present improvements, certain of the parts beingiremoved for the sake of clearness;

Fig. 2 is. a schematic .showingof the improved tap-changing apparatus illustrating the manner of operation thereof, certain of the parts being removed for the sake of clearness;-

Fig. 3 is an elevational sectional view of 118 improved tap-changing apparatus in Fig. 4 is a sectional view, the section being taken on the line 4-4 in Fig. 3;

Fig. 5 is an enlarged fragmentary plan view of the improved tap-changing apparatus;

Fig. 6- is a sectional view'of the improved tap-changing apparatus,- the section being taken on the line 66 in Fig. 5;

Fig. 7 is adetail sectional view, the section being taken on'th'eline 7-7 in Fig. 5;

Fig. 8 is a view similar to Fig. 7, illustrating a modification;

' Fig.9 is a plan view of Fig.8;

Fig. 10 is an elevational view, looking toward the left in'Fig. 8;

Figs. 11, 12 and 13 are views similar to Fig. 1. illustrating various modifications;

Fig. 14is a view similar to Fig. 4, showing'details of the control mechanism in the system shown in Fig. 12; and

Fig. 15 is a view similar to Fig. 4, showing details of the control mechanism in the system shown in Fig. 13.

Referring now to Fig. 1, the transformer 10 includes the primary winding 11 connected across the alternating-current supply lines 12 and 13, and the secondary winding 14 having the voltage taps 15, 16, 17, 18 and 19.

The tap-changing apparatus for the switch, designated generally by the reference numera1 20, comprises the switch contact 21 connected to supply line 13 and the switch contacts 22, 23, 24, 25 and 26 connected, respectively, to voltage taps 15, 16, 17 18 and 19; and the operating member comprising the switch elements 2'7 and 28 fixed on shaft 29 for rotary movement together and electrically connected to suitable rings 30 and 31 which are engaged by suitable brushes 32 and 33 providing connection between the switch elements and the ends 34 and 35 of an auto-transformer winding 36 having the mid-tap 37.

A switch device 38 is associated with switch mechanism 20 and provided with the contacts 39 and 40 connected, respectivel with the ends 41 and 42 of secondary win mg 14, the switch device having electrical connection with switch contact 21 and being supported for pivotal movement upon the pin 43.

v47 provides for left-hand movement of the rack to efiect clockwise rotation of the switch member.

The load is connected across'lines 12 and 48, the latter being connected, as shown, to midpoint 37 of the auto-transformer.

The operation of the system thus far described will now be explained. In Fig. 1, the switch member 2728 is shown in one of its extreme positions to provide for full or maximum boosting action of transformer 10 with respect to the load line 1248, at which time switch device 38 will be in engagement with contact 40 to establish an operating connection between switch mechanism 20 and the end 42 of winding 14. In this position of member 2728, the switch elements comprising the same are bridged by contact 22 to short-circuit winding 36so that the voltage at mid-tap 37 will be equal to that at tap 15.- If the load diminishes, the load voltage is decreased correspondingly by excitation of winding 46, in the manner hereinafter explained, to effect counter-clockwise rotation of member 2728 through such angular dis tance as is necessary'to bring the load voltage back to normal value.

With member 2728 bridging the switch contacts 22 and 23, as shown in Fig. 2,'winding 36 will be connected across taps 15 and 16, so that the voltage at mid-tap 37 will be equal to a value intermediate the voltage values at taps 15 and 16. i

In the position of switch member 27'-28 in which the switch elements are both in contacting engagement with contact 23, and winding 36 accordingly short-circuited thereby, the voltage at mid-tap 37 will be equal to that at tap 16. I

When switchelements 27 and 28 are moved into position to bridge the contacts 23 and 24, the voltage of load line 12-48 will be still further decreased, at which time the voltage at mid-tap 37 will be equal toa value intermediate the voltage values at taps 16 and 17.

In like manner, continued counter-clockwise movement of switch member 2728 will provide for still further decrease in the voltage at mid-tap 37 in steps, the next lower voltage being that at tap 17 in which switch elements 27 and 28 are bridged b switch contact 24; the next lower voltage eing intermediate the voltages at taps 17 and 18, at which time the switch elements will be in position to bridge the contacts 24 and 25; the

0 next lower voltage being that at tap 18, at

which time switch elements 27 and 28 will be bridged by switch contact 25; the next lower voltage being intermediate the voltages at taps 18 and 19, at which time switch elements 27 and 28 will bridge the contacts 25 and 26; the next lower voltage being that at tap 19, at which time switch elements 27 and 28 will be bridged by switch contact 26; the next lower voltage being intermediate the voltages at tap 19 and the winding end 42, at

which time switch elements27 and 28 will bridge the contacts 21 and 26. When the switch member is moved into position in which the switch elements 27 and 28 are bridged by contact 21, winding 36 will be short-circuited through this contact. The load voltage across lines 12 and 48 will then be equal to the supply voltage across lines 12andl3.

During further counter-clockwise rotation of the switch member, a suitable lug or pro- ,jection 49 carried by switch element 27 enters between the spaced k gs 50 and 51 forming part of switch element 38, and by engagement with leg 50, as ,more clearly shown in Fig. 5, causes clockwise movement of switch 38 into contacting engagement with contact 39, at which time both switch elements 27 and 28 will be in contact with and bridged by switch contact 21.

Further counter-clockwise movement of member 27-28 will provide for still further reduction in the load voltage on account of the reversal of switch 38 to establish an operating connection between the switch mechanism 20 and the other end 41 of winding 14. Transformer 10 will now have a bucking action with respect to the supply voltage. When switch elements 27 and 28 bridge the contacts 22 and 21, winding 36 will be connected across end 41 and tap 15 of winding 14. The voltage at mid-tap 37 will then be intermediate the voltages at end'41 and tap 15.

Upon further movement of switch elements 27 and 28 to the position in which the same are bridged by contact 21, winding 36 will be short-circuited by this contact so that the voltage at mid-tap 37 will be equal to that at tap 15.

The next lower voltage will be provided when switch elements27and 28 are inposition to bridge the contacts 23 and 22, at,

which time the voltage at mid-tap 37 willbe intermediate the voltages at taps 15 and 16.

In like manner, it will be understood that continued counter-clockwise movement of operating member 2728 will provide for still further decrease in the voltage at midtap 37, the respective succeeding values being equal to the voltage at tap 16, next to a voltage intermediate the voltages at taps 16 and 17, next at a voltage equal to that at tap 17, next at a voltage intermediate the voltages at taps 17 and 18, next at a voltage equal to that at tap 18, next at a voltage infinally at the minimum voltage equal to the voltage'at tap 19 when switch elements 27 and 28 are both in contacting enga ement with contact 26 and are bridged there y, the switch member 2728 then being in its'other extreme position in which full bucking action of winding 14 is obtained.

During the first revolution of switch member 2728 in a clockwise direction, the load termediate the voltages at taps 18 and 19, and q 0nd clockwise revolution, the projection 49 carried by switch element 27 will first enter between legs 50 and 51 of switch 38 and, by engagement with leg 51, will efi'ect counterclockwise rotation-of switch 38 into contacting engagement with contact 40. .During this second revolution of switch member 27-28, therefore, the switch mechanism 20 will be connected to the end 42 of transformer winding '14, and the voltage increased in steps from the intermediate or' neutral value in the voltage range to the maximum voltage value in which switch elements 27 and 28 are in their extreme position as shown in Fig. 1, and are bridged by contact 22.

From the foregoing it will be seen that in the present improved tap-changing apparatus, the switch elements 27 and 28 constitute means providing for concurrent connection of both ends 34 and 35 of winding 36 with the individual taps of winding 14 or connection of one of the ends of winding 36 with one of the taps concurrently with connection of the other end of winding 36 with another of the taps. In other words, switch member 2728, in the presentembodiment of the invention, provides for conditions in which winding 36 is either short-circuited by the individual taps of winding 14 or is connected across adjacent taps. It will further be seen that switch device 38 and associated parts constitute means operable to establish operating, connections between switch mechanism 20 and either of the end oints '41 and 42 of winding 14, the transormer winding 14 having a boosting action in the system when switch 38 is in contacting enga ement with contact 40 and having a bucking action in the system when switch 38 is in contacting engagement with contact 39.

By reason of this construction and connection, the same portion of winding 14 is effective during different parts of the entire voltage range provided by switch mechanism 20. That is, during the first complete revolution of switch member 27 28 in a counter-clockwise direction, winding ,14 will be effective to-provide for regulation ofthe voltage in steps from the maximum value, in which switch elements 27 and 28 are in their initial position and bridged by contact 22, to the intermediate or neutral value in the voltage range in which the switch elements are both in contact with and bridged by contact 21, at which time the load voltage will be equal to the supply voltage, as explained. During the next revolution of operating member 27-28 in a counter-clockwise direction, rior to which switch 38 is reversed, as explained above, the same portion of winding 14 which was effective before will be efiective again to provide fonvoltage regulation throughout the lower half of the voltage range and in steps from the intermediate or neutral value to the minimum value which is equal to the voltage'value at tap 19. V

The present construction, it will be seen further, provides for a considerably greater number of operating positions or voltagev steps and there are taps to transformer winding 14. Furthermore, atoperating positions in which switch elements 27 and 28 are bridged by adjacent contacts of switch mechanism 20, the current will be equally divided between elements 27 and 28 and the associated connections to ends 34 and 35 of winding 36, so that the switch contacts then operating will have to carry only one-half of the main load current.

Figs. 3 to 7 show in a general way a proposed construction of the system and apparatus shown in Fig. 1. As shown in Fig. 3, it is proposed to mount or support the various parts comprising the present improved system in a single casing 52 having the lower chamber 53 containing the main transformer- 14 and auto-transformer 36, the intermediate chamber 54 containing switch mechanism 20, and the upper chamber 55 containing the actuating and control mechanism for the switch mechanism. The lower chamber contains oil to about the level indicated by line 56 to completely submerge the transformer apparatus, while the intermediate chamber 54, which is entirely independent of the bottom and top chambers 53 and 55 and is sealed therefrom, contains oil to about the level indicated by line 57 so that switch mechanism 20 is entirely submerged and operates at all times in oil. The main transformer leads may be taken out through casing 52 by way of suitablebushings 58, as indicated.

The switch 38 may be comprised of the resilient strips or arms 59 and 60 spaced by and secured to the switch part 61 by rivets 62, these strips or arms carrying at their outer ends complementary contact shoes 63 and 64, 'shaped as indicated, and urged toward each other by the spring action of the arms into firm contacting engagement with contacts 39 and 40.

The switch elements 27 and 28 are constructed, in a similar manner, of resilient strips or arms secured in any suitable manner to an. insulating block or disc 65. For example, in Fig. 7 switch element 28 is indicated as being comprised" of the spring strips or arms 66 and 67 carrying at their outer ends the complementary contact shoes 68 and 69.

For the purpose of preventing arcing action between switch contacts 21 to 26 and the contact shoes cooperable therewith and which form part of switch elements 27 and 28, auxiliary or arcing contacts are provided, the latter being similar to and disposed above and electrically connected to the respective main contacts. Disposed above switch element 28 and electrically connected thereto is the auxiliary or arcing switch element 28' which is secured by rivets 70 to the insulating block or disc 71. The arcing contact shoe 72 is fixed to the outer end of switch element 28' and engages with the arcing contacts. As indicated in Fig. 7, each of the arcing contacts, such as the contacts 21 and 22' associated and electrically connected respectively 'with main contacts 21 and 22, extend slightly beyond the edges of the latter so that the arcing shoe 72 engages and disengages the associated contacts before engagement or disengagement of contact shoes 68 and 69 with contacts 21 to 26 during rotary operating movement of switch member 27-28 in either direction.

An auxiliary or arcing switch element, similar to element 28', is disposed above and electrically connected to the main switch element 27 and, like switch element 28, is secured to the block or disc 71 and disposed for engagement with the auxiliary arcing contacts.

The switch mechanism 20 is mounted on the insulating base 73 forming a partition between chambers 53 and 54, and which is provided with the upwardly extending annular flange 74 through which terminal posts 75 lead to the respective switch contacts 21 to 26 and the associated arcing contacts. The terminal post 76 leads to switch contact 39, while the terminal post 77 leads to brush 33. A similar post (not shown) provides a connection to brush 32. The tubular member 78 is provided with the outwardly extending flange 79 and has a press fit on the bearing post 80 having its lower end portion extending loosely through the center of base 73 for rotary movement therein. The nut 81 threaded on the lower end of post 80 operates to hold the same in assembled relation and for rotary movement with respect to base 73. The rings or discs 30 and 31, insulating discs 71 and 65, and a spacing block 82, are clamped firmly between flange 79 and the nut 83 threaded on the upper end of tubular member 78, as shown.

Shaft 29 may be coupled to the upper end of tubular member 78 by a pin 84.

In the modification shown in Figs. 8, 9 and 10, a plurality of arcing contact shoes 85 to 89 are substituted for the single arcing shoe =72 in Fig. 7, these contacts being secured to the uprightly disposed insulating block securedin any suitable manner to the upper insulating disc 71. Contact shoes 91 to 95, complementary, respectively, to contact shoes 85 to 89, are supported by spring clips or arms 96 secured to the uprightly disposed insulating post 97 secured to the outer portion 98 of the switch contact 99, the latterbeing engaged by the main contact shoes whichcorrespond to the contact shoes 68 and 69 in Fig. 7. A metal insert 101 provides connection with contact shoe 85. Contact shoes 86 and 87 are electrically connected by a metal insert 102, while contact shoes 88 and 89 are electrically connected by a metal insert 103. Contact shoes 91 and 92 are electrically con- I nected by a metal insert 104 and contact shoes 93 and 94 are electrically connected by a metal insert 105, contact shoe 95 being electrically connected with the outer part 98 of contact I of smaller arcs and the arcing action at theindividual arcing contact shoes decreased accordingly.

, The automatic control means, whereby switch mechanism 20 is operated automatically in one direction or the other to maintain the load voltage across lines 12 and 48 substantially constant, will now be described. The relays 107 and 108 are provided, respectively, with windings 109 and 110 connected, as shown, to the voltage transformer 111 having its primary 112 connected across lines 12 and 48 at a point in proximity to the tapchanging apparatus, and to the line-drop compensator of well-known construction and which is indicated generally by reference numeral 113. The arrangement is such that at load conditions during which the load voltage is ubstantially normal, excitation of relay win ing 109 will be such as to hold the associated switch element 114 out of bridging relation with contacts 115, while the excitation of relay winding 110 will be insufficient to effect movement of the assomake this winding effective to cause move ment of switch element 116 into bridging relation with contacts 117.

Upon the bridging of contacts 117 by switch element 116, the winding 118 of relay 119 will be connected to the supply source 120 through winding 46, switch 121 and connection 122. Winding 46 will, therefore, be excited and accordingly become effective to impart right-hand movement to rack 44. Upon such movement of the rack, the shank 123 of the switch 124 will ride up and down the teeth of the rack to effect opening and closingoperation of switch 124, the arrangement being such that when the end of shank 123 is in position between adjacent teeth switch member 27-28 is in one of its operatcontacts, the switch being urged at all times out of bridging relation with respect to the contacts and into seating engagement with rack 44 by the spring 128.

Upon excitation o relay winding 118 and closure of switch 124 upon occurring righthand movement of rack 44, the associated switch element 129 is moved into bridging relation with contacts 130 to complete a circuit between winding 46 and supply 120, independently of contacts 117, such circuit being made through connection 131, contacts 125 and 126, connection 132, contacts 130, relay winding 118, winding 46, switch 121 and connection 122.. In event the resulting righthand-movement of rack 44 and the accompanying counter-clockwise rotation of switch member 2728 provides for decrease in the 9 load voltage to normal at a time when the switch member is in a position intermediate one of its operating positions, and switch element 116 ispermitted to move out of bridging relation with contacts 117, an exciting circuit for winding 46 will be maintained through the contacts 130 and contacts 125 and 126 until the switch member moves by such further amount as to place the same in the next operating position thereof, at which time the switch shank- 123 will be pressed into position between the adjacent rack teeth and switch element 124 moved out a of bridging relation with the contacts 125 and 126 to open theexciting circuit for winding 46.

When switch member 27--28 reaches its extreme position in which the switch elements comprising the same are bridged by contact 26 to provide for full bucking action of winding 14, the switch 121 will be opened through the instrumentality of the lever 133 pivotally mounted at 134 and disposed for engagement by the lug 135 carried b rack 44.

Upon the bridging of contacts 115 by switch element 114, a circuit will be completed between winding 47 and supply 120 through contacts 115, winding 136 of relay 137, switch 138 which will have closed during previous right-hand movement of rack 44, winding 47 and connection 122. Upon excitation of relay winding 136, the switch element 139 associated therewith will be moved into bridging relation with contacts 140 to establish another operating circuit between winding 47 and-supply 120 through connection 131, contacts 125 and 127, connection 141, contacts 140, relay winding 136, switch 138, winding 47 and connection 122, the closed contacts 140 accordingly providing for an operating circuit between winding 47 and supply 120 independently of contacts 115 and the associated switch element 114.

In event, therefore, the occurring lefthand movement of rack 44, accompanied by clockwise rotation of switch member 2728 results in increase of the load voltage to nor mal at a point in the operating movement of the switch member at which the same is intermediate one of the operating positions thereof, in which case excitation of relay windin 109 will be such as to efiect movement 0 switch element 114 out of bridging relation with contacts 115, the exciting circuit between winding 47 and supply 120 will be maintained b the closed contacts 140 and contacts 125 an 127, as explained, until the rack has continued its left-hand movement by such amount as to bring shank 123 of switch 124 in full registration with adjacent teeth of the rack, at which time switch 124 will be moved out of bridging relation with contacts 125 and 127 under the action of spring 128 to open the exciting circuit of winding 47. Upon movement of switch member 27--28 to its extreme position, as shown in Fig. 1, .in which the switch elements comprising the same are in contact with and are bridged by contact 22' to provide for full boosting action of transformer winding 14, lever 133 will be engaged by the lug 142 carried by rack 44 and moved into the position shown to open switch 138.

From the foregoing, it will be seen that automatic means have been provided for effecting operating movement of switch member 27-28 in a clockwise direction upon decrease in the load voltage below normal, and in a counter-clockwise direction upon increase in the load voltage-above normal, the operating movement of the switch member being continued until. the load voltage is restored substantially to normal, the switch 124 and associated parts providing for operation of the switch member in such wise that the same always comes to rest in one of its operating positions in which switch elements 27 and 28 either bridge adjacent switch contacts or are bridged by one of the individual contacts.

When the present improver tap-changing system and apparatus is used in a high-tenment and manner of operation is the same the influence of transformer winding 14 in 7 completed through connection .150, switch having a boosting or bucking action with respect to the supply voltage being made throu h current transformer 143.

In igs. 12 and 14, a proposed construction and arrangement is shown whereby the relays 119 and 137 in Fig. 1 may be omitted, the various connections and parts being given the same reference numerals as similar and corresponding connections and parts in Fig. 1.

Upon movement of switch element 116, in Fig. 12, into bridging relation with contacts 117, an exciting circuit between winding 46 and supply 120 will be established through contacts 117, connection 144, connection 145, windin 46, switch 121 and connection 122. U on t e occurrence of right-hand movement o rack 44, the switch element 146, which is pivotally mounted at 147 and provided with the pro ection 148 disposed in the path of; movement of the rack teeth, will be tilted in a counter-clockwise direction into contacting engagement with contact 149 as the projection 148 rides over each tooth of the rack, Upon engagement of switch element 146 with contact 149, an exciting circuit between winding 46, and supply 120 is established independentlyof contacts 117, such circuit being element 146 and contact 149, connection 145,

winding 46, switch 121 'and connection 122. In event the load voltage is brought back to normal when the switch 'member 27-28, in Fig. 1, is at a point in its operating movement intermediate adjacent operating positions of the switch member, the engaging switch element 146 and Fontact 149'will maintain excitation of winding 46 although switch element 116 will have moved out of bridging relation with the associated contacts 117. The arrangement is such that when the switch member 2728, in Fig. 1, has moved by such further amount as to bring the same'to the next operating position, rack 44 will be in such position that adjacent teeth in the rack receive projection 148 to permit return movement of switch element 146 to its central position under the action of suitable springs 151 whereupon the same is in position out of contacting engagement with both the associated contacts 149 and 152. The action in I the opposite direction is the same, that is,

upon decrease in the load voltage below normal switch element 114 will move into bridging relation with contacts 115 to complete the circuit between winding 47 and supply 120 through contacts 115, connection 153,

146 will cause clockwise pivotal movement I of the same into contacting engagement with contact 152, thereby establishing an operating circuit between winding 47 and supply 120 mdependently of switch 114 and contacts 115, such independent circuit being madethrough connection 150, switch element 146 and contact 152, connection 153, switch 138,

winding 47 and connection 122. During lefthand movement of rack 44, and durin times when the switch member 2728, in ig. 1, is in any position intermediate any of its operating positions, the rack teeth will cause engagement ofswitch element 146 with contact 152. When, however, switch member 2728 is in any of its operating positions, the adjacent teeth then coacting with projection 148 of switch element 146 will be in position to receive the same and permit movement thereof to central position under the action of springs 151.

From the foregoing it will be seen that, in the arrangement in Figs. 12 and 14, the action is the same as in Fig. 1, the switch element 146 and associated parts providing that switch member 2728 always come to rest in one of its operating positions in which the switch elements 27 and 28 comprising the same are either bridged by one of the individual contacts 21 to 26 or bridge adjacent contacts.

In Figs. 13 and 15, proposed connections and arrangements are shown having the same operating action as the connection and arrangement shown in Fig. 1, but wherein an electric motor is employed in lieu of the rack-and-pinion mechanism 4445 and sole noids or windings 46 and 47. In the modification in Figs. 13 and 15, an electric motor 154 is connected to the drive shaft 155 having a worm 156 meshing with worm wheel 157 fixed on shaft 158, the latter corresponding to shaft 29 in Fig. 1. Fixed on drive shaft 155 is the brake drum 159 with which are associated the brake shoes 160 carried by levers 161 pivotally mounted ,at 162. The tension spring 163 is connected to levers 161 as shown, and operates to urge shoes 160 into braking engagement with drum 159. Armatures 164 associated with levers 161 are urged toward each other upon excitation of winding 165 and supply 171 through connection 172, contacts 170, connection 173, the motor field winding 17 4, switch 175, connection 176, relay winding 177, connection 178, contacts 169, connection 17 9, connection 180, brake-releasing winding 165 and connection 181. The motor 154 now operates to impart rotary movement to shaft 158 in a counter-clockwise direction. When the switch member 2728, in Fig. 1, reaches its full boosting position in which the switch elements 27 and 28 are bridged by contact 22, the lug 182 fixed on shaft 158 will engage leg 183 with which the switch-actuating element 185 is provided and impart counter-clockwise movement to the latter into engagement with switch 175 to open the same. During riodsin the rotary movement of shaft 158 w en the switch member 27-28, in Fig. 1, is in a position intermediate any of its adjacent operating positions, the teeth of the gear 186-fixed on shaft 158 will operate to effect engagement of the switch member 187 with the associated contacts 188,189 and 190, the action beingthe same as that between theteeth of rack 44 and switch member 123, in Fig. 1. An operating circuit between motor 154 and supply 171 is thereby established independently of the closed contacts 169 and 170, such independent circuit being made through connection 181, brake-releasing winding 165, connection 180, contacts 190 and 188, connection 191, closed contacts 192, relay winding 177 connection 176, switch 175, motor field winding 174, connection 173, closed contacts 193 and connection 172. In event, therefore, the load voltage be decreased to normal and contacts 169 and 170 accordingl opened before switch member 2728, in Fig. 1, reaches one of its operating positions, an exciting circuit for motor 154 and brake-releasing winding 165 will be maintained through contacts 188 and 190 and contacts 192 and 193 until the switch member has reached the next operating position, at which time switch member 187 will be received between adjacent teeth of gear 186 to permit of opening movement thereof under the action of spring 194.

Upon decrease in the load voltage below normal, excitation of relaywinding 195 will be decreased by such amount as to permit of movement of switch elements 196 and 197 into bridging relation with the respective associated contacts 198 and 199, thereby establishing an operating connection between metor 154 and supply 171 through contacts 199, connection 200, relay winding 201, connection 202, switch 203, field winding 174,

connection 210, contacts 198, connection 172, motor 154, supply 171, brake-releasing winding 165, connection 180, connection 179 and connection 204. Reverse rotation of the motor will now take place to effect counter-clockwise rotation of shaft 158 and accompanying counter-clockwise rotation of switch .member 2728 in Fig. 1. Upon excitation at this time of relay winding-201, switch'elements 205 and 206 will be moved into bridging relation with the respective associated contacts 207 and 208. An exciting circuit between motor 154 and supply 171 will therefore, be established independently of the closed contacts 198 and 199, such independent circuit being made through connection 181, brake-releasing winding 165, connection 180, contacts 190 and 189, connection 209, contacts 208, relay winding 201, connection 202, switch 203, field winding 174, contacts 207, motor 154 and supply 171. It will be seen, therefore, that in event of the occurrence of counter clockwise rotation, shaft 158 operates to effect increase in the load voltage to normal at a point in the operating movement of switch member 2728, in F ig. 1, when the same is in position intermediate any adjacent operating positions, and excitation of relay winding 195 is accordingly increased by such amount as to effect movement of switch elements 196 and 197 out of bridging relation with the respective associated contacts 198 and 199, the exciting circuit for the motor and brake-releasing winding is maintained by switch elements 205, 206 and 187 until switch member 27-28 has reached the next operating position.

During the first counter-clockwise revolution of shaft-158, the lug or projection 182 is received between legs 183 and 184 of switchactuating element 185, and the leg 183 engaged by lug 182 to cause pivotal movement of this element in a clockwise direction to the position shown when leg 184 is in position in the path of movement of lug 182. At the completion of the second revolution of shaft 155 in a counter-clockwise direction, therefore, lug 182 will engage leg 184 to effect further clockwise pivotal movement of element 185 into engagement with switch 203 to open the same. Similarly, during the first clockwise revolution of shaft 155, lug 182 is received between legs 183 and 184, and leg 184 engaged by lug 182 to cause pivotal movement of element 185 in a counter-clockwise direction to the position shown when leg 183 is in position in the path of movement of lug 182.

While several embodiments of the present invention have been illustrated and described, it will be appreciated that various other modifications or changes may be made without departing from the spiritof the invention or the scope of the claims.

The invention claimed is:

1. In a system of the characterdescribed, a transformer winding, switch means operable to render said winding effective to provide for voltage regulation in said system throughout a predetermined voltage range, and second switch means controllable b" said first-named switch means during operating movement of the latter, said second switch means being operable under control by said first-named switch means to establish operating. connections between the same and differentv points in said winding.

2. In a system of the character described, a transformer winding having voltage taps, and switch mechanism connected to said taps and having an operating member supported for rotary operating movement in a given direction through more than a complete revolution and being operable to provide for volt? age regulation in said system throughout-a predetermined voltage range upon,,=;s'i1ch movement of said member and in steps" from the voltage value at one end of said voltage range where said'member is substantially at its initial-operating position to the voltage value at the other end of said voltage range where said member is substantially at its final operating position.

3. In a system of the character described, a transformer winding having voltage taps, a second transformer winding; and switch mechanism comprising switch elements supported for rotary movement together and connected respectively to the ends of said second winding, and switch contacts connected respectively to said taps and arranged about the axis of rotation of said elements for engagement thereby, said contacts being operable individually to bridge said elements upon movement of the same to certain operating positions, adjacent contacts in said arrangement being operable conjointly to bridge said elements upon movement of the same to certain operating positions intermediate said firs't-named positions.

4. Ina system of the character described, a transformer winding having voltage taps, switch mechanism comprising contacts connected respectively to said taps and an operating member movable into contacting engagement selectively with said contacts and having predetermined operating positions for such purpose, means including rack-andpinion mechanism for imparting operating movement to said member, control means for said first-named means, and means operable independently of said control means to effect operating action of said rack-and-pinion mechanism during operating periods of said switch mechanism whereat said operating member thereof is in positions intermediate said predetermined operating positions.

5. In a system of the character described, a transformer winding having voltage taps, switch mechanism connected to said taps and having an operating member supported for rotary operating movement in a given direction through more than a complete revolution and being operable to provide for voltage regulation in said system throughout a predetermined voltage range upon such movement of said member, and a switch device associated with said switch mechanism and operable to establishan operating connection between the same and either end of said winding, and means carried by said member and disposed for engagement with said switch device-to actuate the sameat a predetermined point in the operating movement of said member.'

6. In a system of the character described, transformer apparatus operable to influence voltage conditions in'said system and including a secondary winding having voltage taps, a second transformer winding, means providing for voltage regulation in said system and operable for such purpose to provide for concurrent connection of both ends of said second winding with certain of the individual taps or connection of one of such ends with certain of said taps concurrently with connection of the other of such ends with another of said taps, and means responsive to abnormal conditions in said system and operable upon occurrence of such conditions to effect operation of said first-named means in such wise as to restore such conditions to normal.

7 In a system of the character described, transformer apparatus operable to influence voltage conditions in said system and including a secondary winding having voltage taps, a second transformer winding, means providing for voltage regulation in said s stem and including a switch member for suc purpose supported for operating movement in opposite directions and having various operating positions and being operable when in such positions to provide for concurrent connection of both ends of said second winding with certain of the individual taps or connection of one of such ends with certain of said taps concurrently with connection of the other of such ends with another of said taps, and means responsive to abnormal conditions in said system and operable upon occurrence of such conditions to effect operating movement of said member in such direction as to effect restoration of normal operating condition in said system.

8. In a system of the character described, transformer apparatus operable to influence voltage conditions in said system and including a secondary winding having voltage taps, a second transformer winding, means providing for voltage regulation in said system and including a switch member for such purpose supported for-operating movement in opposite directions and having various operating positions and being operable when in such positions to provide for concurrent connection of both ends of said second winding with certain of the individual taps or connection of one of such ends with certain of said taps concurrently with connection of the other of such ends with another of said taps, means responsive to abnormal conditions in saidsystem and operable upon occurrence of III said operating such conditions to efiect operating mow ment of said member in such directlon as to efiect restoration of normal operating condition in said system, means operable independently of said second-named means to effect such movement of said member, and means operable to render said third-named means efieetive when said switch member is intermediate said operating positions and to render said third-named means non-efiective when said switch member is substantially in 'tions thereof.

In witness w ereof I hereto aflix my signature this 19th day of April, A. D. 1929.

LELAND H. HILL. 

